The present invention provides a material usable as antistatic agent for film. Since it is excellent in transparency and water resistance, when it is coated, for example, on the surface of support of film photosensitive materials, there is provided good antistatic properties before and after development treatment without giving adverse effects on the characteristics of photosensitive materials and thus, this antistatic agent can be suitably used for general film photosensitive materials which utilize silver salts.
Hitherto, various antistatic agents have been available. Some of them can exhibit antistatic properties of a certain degree at the stage before development treatment by introducing them, for example, into gelatin which constitutes photosensitive materials, but these are all poor in water resistance and when they are merely mixed with gelatin and the mixture is coated and dried, they usually fall away from the photosensitive materials after subjected to development.
Importance of antistatic agent in photosensitive materials is inhibition of generation of static marks, troubles in conveyance caused by static sticking of the photosensitive materials, and statical sticking of dusts before development. Similarly, for films after subjected to development, if no antistatic agent is present, there may be also serious problems such as defects in images caused by sticking of dusts in contact printing to PS plate in the case of films for plate making.
In an attempt to solve these problems by providing an antistatic layer having water resistance, a method has been proposed for enhancing water resistance of antistatic film by adding a polyfunctional aziridine to an antistatic polymer into which a carboxyl group is introduced and crosslinking them as disclosed in Japanese Patent Kokai (Laid-Open) Nos. Sho 55-84658, 56-92535, 61-174542, and 61-174543. However, aziridine compound is unstable and, when added to a coating solution, causes change of properties of the coating solution with time and besides, the compound has the problem of toxicity. Thus, this compound has various difficulties in use at the production site.
Furthermore, effects of the antistatic agent on characteristics of photosensitive materials are also important and direct introduction of antistatic agent in photosensitive layer often causes reduction of sensitivity and fogging of background.